This invention relates to the removal of tissue from the body such as for example removal of cataracts from the eye.
It is known to remove diseased tissue from the body by fragmenting, crushing or otherwise making the tissue flowable while in the body and then aspirating it. In one known class of surgical techniques of this type specifically intended for the removal of cataracts: (1) an incision is made along the superior corneal margin from about 10 to 2 o'clock (12 o'clock is the location closest to the top of the head of the patient) approximately 10 mm in chord length; (2) an incision is made in the capsular wall; and (3) the cataract is removed. The anterior chamber is maintained substantially formed during the operation by means of a continuous inflow of irrigating solution.
In one prior art technique of this class for removing a cataract, the nucleus is expressed out of the eye and the cortex is removed by a process of irrigation and aspiration. In another prior art technique of this class for removing the cataract, the nucleus is removed with a vectis and about 0.1 milliliter of viscoelastic compound or irrigating fluid is introduced into the capsular bag to separate the capsular walls. With the capsular walls separated, a wedge of the cortex is engaged in the aspiration port of a cannula and peeled toward the center and then aspirated to remove it. This process is repeated so that the layers of the cortex are peeled and then aspirated inwardly through the cannula, layer by layer, until the intact capsular bag (except for the horizontal incision) is completely empty and clean.
This technique of removing the cataract is disclosed by Anis, Aziz Y., "Illustrated Step-by-Step Description of the Anis Dry Extra Capsular Cataract Extraction Technique With In-the-Bag Lens Implementation"; Seminars in Opthalmology, v. 1, N. 2 (June), 1986, pp. 113-129 and the technique is compared with other such techniques of this class.
Two prior art types of instruments which aid in the fragmentation and aspiration of the lens nucleus to permit extraction through a small incision are machines disclosed in U.S. Pat. No. 3,589,363 to Anton Banko et al.; U.S. Pat. No. 3,902,495 to Steven N. Weiss; U.S. Pat. No. 3,693,613 to Charles Kelman et al.; and U.S. Pat. No. 4,041,947 to Steven N. Weiss et al. These machines are intended in the prior art to fragment a lens nucleus using ultrasonic vibrations to aid the irrigation/aspiration of the lens. The ultrasonic vibrations laterally reciprocate the tip of an instrument to fracture the cataract after which it can be aspirated.
A further type of machine is disclosed in U.S. Pat. No. 4,908,015 issued to Anis on Mar. 13, 1990. This patent describes a machine that rotates a solid member having blades extending from it to grind the lens.
These tissue removal techniques have several disadvantages, such as: (1) the machines used in the techniques risk tearing the capsular wall with the reciprocating ultrasonic vibration tools or with the rotating blades; (2) under some circumstances, they require large incisions in or removal of parts of the capsular wall; and (3) they may require the use of several different instruments and/or machines.
Still another type of prior art technique for removing cataracts uses a machine disclosed in U.S. Pat. No. 3,996,935 to Banko issued Dec. 14, 1976. This type of machine has cooperating jaw-like members, one of which rotates inside the other to break up the lens by shearing sections of it. It aspirates fragments through the instrument. This type of instrument has a disadvantage in that it can break the capsular wall and is relatively complex. Part of the disadvantage comes from the teaching that it may be rotated manually or mechanically without a corresponding teaching of the rate of rotation required for efficient use.
Still another prior art instrument includes a small rotary magnetic cutter that is injected through the capsular wall and a means for applying magnetic fields that control the magnetic cutter in position. The small magnetic cutter is rotated as it moves from position to position in the capsular bag and to abrade or cut the lens that is to be removed.
This instrument has several disadvantages, such as: (1) it is relatively complicated and expensive because of the need to remotely control the small cutter; and (2) does not incorporate any mechanism for aspirating the lens particles as they are abraded from the lens.
In still another prior art device disclosed in U.S. Pat. No. 4,002,169, small retractable wires are rotated in a range of 5 rpm to 16,000 rpm. There is no teaching of selecting the speed for surface discrimination and the device relies on blunt surfaces to avoid damage to the capsular wall instead. This device has the disadvantages of: (1) providing a relatively slow cutting velocity range with blades not shaped for cavitation or turbulance; (2) not providing a range of velocities sufficient to form small particles that can be aspirated through a small hole; and (3) not providing for aspiration during fragmenting, thus blocking visibility with particles.
Each of these prior art types of instruments includes a handpiece and a console. The handpiece is held by the surgeon and includes an operative tip that, at one point in time, enters the capsular sac to fragment and remove the cataract. The console includes controls for the handpiece such as those that control the direction of movement and speed of movement of the tip, rate of flow of liquids, the suction or aspiration pressure and the drivers that apply power to the hand-piece at the appropriate values. Generally, the consoles are designed together with a particular type of hand-piece used in a specialized technique of ocular surgery.
A still further type of instrument is disclosed in U.S. Pat. No. 4,504,264 to Kelman issued Mar. 12, 1985. This patent discloses an instrument that reciprocates a cutting tip ultrasonically and oscillates it rotationally about its longitudinal axis at a rate of one hertz through an angle of between five degrees to 60 degrees.
A similar United States patent, U.S. Pat. No. 5,176,677 to Wuchinich describes oscillation through a larger arc and states that the rotational motion is not limited as to direction or speed. It describes a device in which rotation of a beveled tip cuts tissue with reversal accommodating asymmetrical morphology to cut tissue that is more easily separated from one side than the other. This patent teaches that rotation from 61 to 360 degrees is sufficient for most purposes but rotation through any arc is possible through appropriate control but does not teach any mechanism or range that is preferable other than the motor being capable of operating from zero to 200 r.p.m. but as much as 3,000 r.p.m. with an appropriate bearing.
Because of dwell time at each change of rotational direction, the repeated changes of direction and speed limitations inherent in the direction changes, these two instruments do not provide the advantage of positive breaking of the tissue into particles small enough to not cause plugging of the tip nor impede visibility.
The prior art arrangement has several disadvantages, such as for example: (1) it is difficult for the surgeon to use the most modern techniques without investing substantial amounts of money in purchasing additional consoles for the newer instruments; (2) for each new handpiece designed for a particular technique, the surgeon must adapt to different controls in the console itsseff rather than relying upon controls with which he is already familiar; (3) the handpieces are subject to plugging, poor visibility into the eye and excessive pressure on the capsular wall from movement of large particles; (4) different equipment is necessary to remove vitreous liquids; (5) the aspirating force pulls large masses of tissue when the tip is normal to the tissue, thus occluding the opening; (6) deep coring is not possible to break the tissue into particles; and (7) vitreous liquids and semisolids are not absorbed but pull back when aspirating pressure is released.